State environmental and energy agencies require strict compliance with laws and regulations regarding fuel storage and conveyance, in particular regarding containment of fuel within the pipes and other components beneath the ground surface at gas stations. Piping systems for conveying the fuel between the underground tanks and dispensers must be pressurized and vacuum sealed to detect and contain leaks therein.
Referring to FIG. 1, there is shown a common dispenser sump connection system 10 below a fuel dispenser 12 at a gas station. Fuel is conveyed from a tank 14 through a primary inner pipe 16, traditionally two inches in diameter, into a dispenser sump 18 below the fuel dispenser 12. Once inside the dispenser sump 18 the inner pipe 16 continues through an elbow joint 20 to a connecting inner pipe 22, which couples to a shear valve 24 located at the bottom of the fuel dispenser 12. The shear valve 24 prevents fuel spills or leaks in the event that the fuel dispenser 12 is displaced from the dispenser sump 18.
A secondary outer pipe 26, traditionally three inches in diameter, encloses the inner pipe 16 from the tank 14 to the dispenser sump 18. The outer pipe 26 prevents fuel from entering into and contaminating the groundsoil and/or the atmosphere. The interstitial space between the outer pipe 26 and the inner pipe 16 is either pressurized or vacuum sealed to provide additional protection against leaks.
Although the outer pipe 26 contains any leaks between the tank 14 and the dispenser sump 18, the outer pipe 26 terminates into a boot at the dispenser sump 18, leaving the inner pipe 16 is exposed inside the dispenser sump 18. Therefore, there are no safeguards to detect or contain leaks that occur inside the dispenser sump 18, which can result in leaks into the groundsoil surrounding the dispenser sump 18 and/or into the atmosphere. Recently, regulations have been passed in several states such as California which require safeguards be installed to prevent leaks from dispenser sumps. Currently the approved safeguards require retrofitting the existing dispenser sump with the equivalent of an outer sump around the dispenser sump within the space between the outer and inner sump being either pressurized or vacuum sealed, or replacing the existing dispenser sump with a double-walled pressurized sump. The cost to install the outer sump or replace the existing sump costs approximately $2,000 minimum per dispenser. Considering that most gas stations have multiple dispensers, the cost to retrofit the existing sumps to bring them into compliance can be substantial.
The present invention comprises a dispenser sump connection system which overcomes the foregoing and other difficulties which have long since characterized the prior art. In accordance with the broader aspects of the invention, an outer and inner flexible connector system provides protection against fuel leakage from the dispenser sump. The inner flexible connector connects the primary inner pipe to the shear valve. The outer flexible connector completely encloses the inner flexible connector from the sump wall to the shear valve. The interstitial space between the outer flexible connector and the inner flexible connector is pressurized and/or be vacuum sealed thereby preventing any fuel leakage into the dispenser sump.
The outer and inner flexible connector system can be retrofitted inside existing dispenser sumps at a minimal cost per dispenser. The present invention provides the high level of protection against leakage required by state environmental agencies and eliminates the need for installing an outer sump or retrofitting with a double-walled sump.